[mythtv-users] One disc drive seems fine

[jzigpublic]

On 12/23/2011 11:52 AM, Josh Mastronarde wrote:
>
> On Fri, Dec 23, 2011 at 6:44 AM, Paul Gardiner <lists at glidos.net 
> <mailto:lists at glidos.net>> wrote:
>
>     Just upgraded my girlfriends combined FE/BE to play HD in the UK.
>     Added a Geforce 210 for playback and a PCTV 290e USB stick for
>     recording. It has just one disc drive for OS and recordings.
>     I expected problems, but I experimented last night. Seemed
>     to be able to handle 4 simultaneous HD recordings and one playback
>     with no apparent difficulty. It's just a 500GB drive, so I
>     guess she might find it tight on space, but performance-wise
>     it seems fine. Just thought I'd feedback to the list.
>
>
>
> Add me to the list of those who've always run one drive with no 
> issues, in various sizes, since 2004 -- and the current one is a 1.5TB 
> WD "green", i.e. slower RPM, drive.  Current system has a dual-tuner 
> HDHomerun recording ATSC.
>
> A quick search for specs for one of these WD drives shows a write 
> bandwidth of ~100MBytes/sec (a .  An HD ATSC stream maxes out at 
> ~20Mbits/sec, or 2.5MBytes/sec.  Yes, thrashing with multiple threads 
> accessing different parts of the disk is going to reduce the actual 
> available bandwidth significantly, but even 2 streams recording plus 2 
> streams playing is only 10% of the theoretical max, which should leave 
> plenty for database and OS access and the switching overhead, 
> especially with a 32+MB cache (effectively ~12 seconds worth).
>
> I don't doubt that systems with many more/higher bandwidth recorders 
> or more frontend clients could run into issues, or that overall 
> interactive response could be slightly better (especially if you're 
> using the machine for other work also) with mutliple drives, but I 
> haven't seen any evidence that it's *required* for a general purpose 
> backend/frontend machine.
>
> Josh
>
+1 here.  Been using MythTV for years on a single drive combined 
frontend/backend with no problems.  Current configuration is 3 atsc 
over-the-air tuners (a dual hdhomerun and a single pchd3000 pci atsc 
tuner) and a 1 Terabyte drive, 2 gigs ram, Nvidia GForce 210 pcie video 
card using HDMI out.

I routinely record 3 HD channels at once while playing back a previous 
recording at 1080P.  Playback is flawless.  Currently using Mythbuntu, 
but I have used KnoppMyth and LinHes with a single drive without 
problems too

Ziggy.

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